Method of producing moistureproof fiber containers



March 12, 1940. D. s. MAGILL METHOD OF PRODUCING MOISTUREPROOF FIBER CONTAINERS Filed Nov 17, 1937 2 Sheets-Sheet l T'TORNEYJ March 12, 1940. MAGlLL 2,192,923

' METHOD OF PROD UCING MOISTUREPROOF FIBER CONTAINERS Filed Nov. 1'7, 193? 2 Sheets-Sheet 2 ATTORNEY5 Patented Mar. 12, 1940 UNITED STATES PATENT OFFICE METHOD OF PRODUCING MOISTUREPROOF FIBER CONTAINERS Donald G. Magill, Great Neck, N. Y., assignor to American Can Company, New York, N. Y., a corporation ofNew Jersey Application November 17, 1937, Serial No. 175,129

. 2 Claims.

the plies of paper board comprising the body walls of such containers. A weakness in this construction is that moisture is liable to gain a foothold in the body wall exterior to the asphalt film and when a foothold is gained there is considerable danger thatthe moisture will eventually pass through the asphalt film into the interior or through the top and bottom seams.

Another common expedient employed in the manufacture of fiber containers, in an endeavor to render the container moistureproof, is the wrapping of the container in a moistureproof paper. A weakness of this construction, aside from the fact that it is very expensive, is that moisture from the exterior usually is able to penetrate through the folds.

The present invention contemplates a method of making an inexpensive fiber container which overcomes these difficulties by preventing moisture from gaining an initial foothold in the body wall. For all practical purposes containers 35 formed according to the steps of the invention completely prevent passage of moisture through the body wall. A package of such high degree moistureproofing qualities is particularly desirable for containing commodities which are par- 0 ticularly susceptible to moisture.

50 with inexpensive waxes or moistureproof lacquers which make a dense film on the paper and which are preserved in continuity by the imperviousness of the paper, the combination of the asphalt and the continuous dense film of wax or lacquer on the impervious paper providing an impenetrable protective coating against moisture for the container contents.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Figure l is a perspective view of one form of apparatus for carrying out the various steps of the instant method invention;

Fig. 2 is an enlarged sectional detail of a portion of a container manufactured in accordance with the steps of the method invention; and

Fig. 3 is an enlarged fragmentary plan View of a portion of the apparatus illustrated in Fig. 1.

In accordance with the instant method invention a continuous moistureproof tube preferably spirally wound is produced from which can bodies may be cut off at any desired length. The tube and the resulting can body are preferably of three ply thickness and are made from three separate strips or webs of fibrous material. These strips are indicated in the drawings by the letters A, B and C. Strips A and B may be any suitable can body fiber stock and when wound into the tube constitute, respectively, an inner and an intermediate ply .of the finished tube. Strip C is preferably a thin parchment, glassine or other greaseeproof or hydrolized paper which has been coated on its two surfaces with different moistureproofing materials. This strip constitutes the outer or third ply of the can body.

Strip A is first spirally wound into tube shape with the adjacent edges of the strip abutting.

Strip B is coated on its inner surface with a suitable adhesive and is wound around the tube so far formed in a spiral fashion with its adjacent edges abutting and overlapping the edges of the strip A, the adhesive providing a suitable bond between the strips so applied.

Before the strip C isapplied to the can body tube it is coated on its inner surface with a hot asphalt adhesive and on its outer surface with a suitable wax or moisture proof lacquer. Neither asphalt nor wax penetrates into the treated, greaseproofed fiber. The coated strip C is then wound on the body tube in a spiral direction parallel to that of strip B and with its adjacent edges overlapping, the strip 0 being drawn taut while winding. This taut winding brings the outer ply of the tube into tight fitting engagement with the intermediate ply and provides for sealing down the overlapping edges of the strip C, the

asphalt still being hot and plastic so as to effect a moisture-tight joint.

It has been found that low cost waxes such as commercial parafiin, or nitrocellulose lacquers with wax base and/or lacquers having a plyolite resin base are excellently suited, from the standpoint of efiiciency and economy, in moistureproofing the impervious paper strip. The impervious nature of the paper insures and preserves the continuity of the wax or lacquer coating and this is especially important at the overlapped edges of the strip which have heretofore been the most difficult region to moistureproof. This wax or lacquer combined with the impervious paper and with the asphalt adhesive when applied to a tube as described above produces a protective coating which is entirely moistureproof.

Containers made from such body stock and thus moistureproofed have been packed withproducts highly susceptible to moisture such as powdered malted milk, malt sugars, etc., and have been subjected to tests in humid atmospheres of about 95% relative humidity over extended periods of time and have been transported on trucks for several weeks from place to place, unloaded and reloaded again, under all kinds of weather conditions during which time the containers have been directly and repeatedly subjected to water and yet when opened the contents of these containers showed that they were unaffected by any moisture and in perfect condition.

By way of illustrating a preferred form of apparatus for carrying out the steps of the instant method invention the drawings disclose the principal parts of a spiral tube winding machine generally indicated by the numeral ll (Figs. 1 and 3). The winding machine includes a stationary cylindrical mandrel l2 one end of which is clamped in a block l3 carried on a main frame M which supports the various parts of the machine. The other end of the mandrel is floatingly supported in any suitable manner.

The inner ply or strip A of fiber is fed from any suitable source of supply such as a roll 5 preferably supported on a bar I! carried in a sub-frame l8 disposed adjacent the winding machine H. The strip is directed onto the mandrel l2 of the winding machine at an angle which will bring adjacent edges of the wound strip into abutting engagement with each other as best shown in Fig. 3. Guides l9 bolted to the winding machine frame I 4 guide the strip into place on the mandrel.

As the strip A is wound and advanced along the winding machine mandrel the intermediate ply or strip B of fiber is wound over the top of it. This is the usual practice in spiral tube manufacture. Like strip A, strip B may be fed from a roll 2| which is supported on a bar 22 carried in an auxiliary. frame 23 disposed adjacent the winding machine H on the opposite side to that on which the sub-frame I8 is located.

Adhesive is applied to the inner surface of the strip B by a roller 25 which is rotatably carried in an adhesive pot 26 disposed between the auxiliary frame 23 and the winding machine ll. The roller 25 rotates in a bath of adhesive in the pot 2G and carries the adhesive up onto the strip B as the latter is fed-from its roll 2|. Other rollers 2'! guide the strip in its travel over the adhesive pot.

The adhesive coated strip B while being wound on the tube on the mandrel l2 of the winding machine is guided at the proper angle so that its adjacent edges will abut each other. For this purpose a guide 3| is secured to the side of the winding machine frame l4.

Winding and advancing of the tube on the mandrel 12 is effected by an endless belt 33 which is obliquely trained around the mandrel as best shown in Fig. 2. The belt takes over a pair of pulleys 34 mounted on vertical shafts 35 carried in suitable bearings formed in brackets 36 secured to the winding machine frame l4. The pulleys are rotated in unisonby gearing generally indicated by the numerals 38, 39 (Fig. 1), the driving gears being carried on a cross-shaft 4i. Power is transmitted to the gearing by way of a pulley 42 carried on the outer end of a drive shaft 43 mounted in bearings 44 secured to the machine frame M. The inner end of the drive .shaft carries a bevel gear 45 which meshes with purpose. Like the strips A and B, strip C may be fed from a roll 48 carried on a bar 49 supported in a side frame 5| disposed adjacent the winding machine I l and the auxiliary frame 23.

The asphalt adhesive and the wax or lacquer are applied to the strip in a double deck applying device 53 which is located between the side frame 5| and the winding machine II. This device includes an upper tank 55 which contains a bath of hot asphalt adhesive and a lower tank 56 which contains the wax or lacquer. The wax is also hot but when lacquers are used they are preferably applied cold. Suitable heating elements 5? are provided under each tank for keeping its contents hot. The upper tank 55 carries a pair of guide rollers 59 and an adhesive applying roller 5d, the latter roller dipping into the hot adhesive. The lower tank carries a plurality of guide rollers 62 and also a wax or lacquer applying roller 63 which is partially immersed in thekhot wax or cold lacquer contained in the tan The strip 0 in being. advanced toward. the mandrel l2 of the winding machine first passes over the guide rollers.62 and the wax or lacquer applying roller 63 and thereby picks up a coating of wax or lacquer on the surface of the strip which will be on the outside of the tube when the strip is wound thereon. Passing from the wax or lacquer tank the strip moves over the guide rollers 59 and the adhesive roller GI and picks up a coating of the asphalt adhesive on the opposite surface of the strip. This latter surface will directly contact the outer surface of the strip B on the tube..

The strip C thereafter passes onto the tube being wound while the asphalt is still plastic. The threading of the strip C over the various rollers associated with the applying device 53 assists in holding the strip taut and also holds the strip in tight engagement against the tube while the strip is being applied. This presses the asphalt adhesive into close binding association with the tube and firmly seals down theoverlapping edges of the strip.

The moistureproof tubing resulting from the winding of separate and different types of strips of fiber may be cut into finished can bodies of any desired length in any approved manner.

Metal or fiber ends 65 may be attached to the body as shown in Fig. 2 in any suitable manner as by a seam 66 thus completing the container. The material of the can ends 65 at the seams 66 is preferably embedded into the body in such a manner as to prevent breaking of the wax or lacquer coating on the outside of the body but still tightly enough to prevent moisture from seeping into the container through the thereby produced.

The tight seams at the ends of the finished can and the moistureproof outer layer on the body thus prevents any moisture from getting into the fibers of the can body and thus prevents these fibers from acting as reservoirs for storing up an accumulation of small degrees of moisture which might otherwise collectively affect the contents of the can. It has been found that such a method of moistureproofing the outside area of containers thus prevents the building up of moisture in the can walls and is therefore much more effective as when applied to the inside of the container.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the process hereinbefore described being merely a preferred embodiment thereof.

joints I claim: 1. A method of producing moistureproof fiber containers which comprises winding a plurality,

of strips of fiber into a continuous tube bonded with adhesive, feeding a strip of parchment toward said tube, superficially applying a non-impregnating coating'of wax to the outer surface of said parchment strip, superficially coating the inner surface of said parchment strip with asphalt adhesive, and applying said coated parchment strip to said tube with the asphalt adhesive coated surface in contact with said tube and with its edges overlapped and sealed together by said asphalt adhesive for providing a bond between the engaged parts of the tube and the strip.' I

2. A method of producing moistureproof fiber containers which comprises winding a plurality of strips of fiber into a continuous tube bonded with adhesive, feeding a strip of parchment toward said tube, superficially applying a nonimpregnating coating of moistureproof lacquer to the outer surface of said parchment strip, superficially coating the inner surface of said parchment strip with asphalt adhesive, and applying said coated parchment strip to said tube with the asphalt adhesive coated surface in contact with said tube and with its edges overlapped and sealed together by said Iasphalt adhesive for providing a bond between the tube and the strip.

poNAnp G. MAGILL. 

